User interfaces for mobile and wearable medical devices

ABSTRACT

Graphical layouts, algorithms, and methods are introduced herein to implement user interfaces for mobile and/or wearable medical devices. In one aspect of the present invention, new graphical layouts are introduced for simplified presentation of time-dependent patient data. In another aspect of the invention, methods and algorithms are introduced to acquire, extract and present relevant features of patient data in real-time in order to simplify the graphical presentation and interpretation. In another aspect of the invention, elements of a multi-modal user interface are introduced in order to simplify and minimize the user&#39;s interaction with the medical wearable device. In yet another aspect of the invention, further methods are introduced for real-time interaction between a user or several users and a wearable or several wearable medical devices. In one embodiment of the present invention, a smartphone, a smart watch, a head-mounted device or similar devices can be used to acquire and display in real-time patient data, e.g., electrocardiogram and relevant features, e.g., heart rate, etc. In another embodiment of the present invention, smartphones, smart watches, head-mounted devices or similar devices can be used to share in real-time the patient data.

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/027,801 filed on Jul. 23, 2014, the disclosure of which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The invention relates in general to simplified user interfaces formedical devices and in particular to simplified user interfaces whichcan be used for mobile and/or wearable medical devices. In the contextof the present invention, mobile medical devices are medical deviceswhich make use of mobile platforms, e.g., smartphones or tablets. In thecontext of the present invention, wearable medical devices are medicaldevices which make use of wearable platforms, e.g., smart watches,head-mounted devices, contact lenses, and other wearable objectsintegrating medical technology functions, etc. The invention introducesalgorithms and methods which allow for the real-time data acquisitionand extraction of relevant features of the clinical data for simplifiedpresentation and interpretation. The invention further introducesgraphical layouts optimized for the real-time display of clinical dataon mobile platforms, e.g., smartphones, smart watches, head-mounteddevices, and similar wearable devices. The invention further introducesmethods of real-time interaction between users and wearable medicaldevices in order to allow for simplified interaction and easy sharing ofclinical data.

BACKGROUND OF THE INVENTION

Currently there exists a growing tendency to use mobile platforms andwearable devices for medical applications. With such devices, the userinterface paradigm is changing in several ways when compared totraditional medical devices. For example, the display/screen becomessmaller with mobile platforms and wearable devices, if a display existsat all. With mobile platforms and wearable devices, a range of differentand/or new user interaction methods become more frequent compared withtraditional medical devices, e.g., touch screens, voice control, gesturecontrol. With mobile platforms and wearable devices, the ability toaccess information at remote locations and to share information inreal-time increases when compared to traditional medical devices. Forall the above mentioned reasons, new user interfaces for wearable andmobile medical devices are needed in order to optimize the real-timeinteraction, acquisition, presentation and interpretation of medicalinformation using the new paradigm of mobile and wearable technology.

Several U.S. patents and patent applications describe aspects of usingportable, mobile and wearable devices for medical applications. Forexample, in U.S. Pat. No. 7,261,691 “Personalized Emergency MedicalMonitoring and Transmission System”, a portable medical system forreal-time applications is described without any emphasis on its userinterface. In U.S. Pat. No. 8,326,651 a user interface is described formanaging medical data focused on off-line use, i.e., not in real-time.In U.S. Pat. No. 8,521,122 a user interface for mobile devices isintroduced for displaying emergency information. However, this inventiondoes not address any aspects regarding the real-time acquisition ofpatient data nor does it address aspects related to extracting relevantinformation in order to simplify the user interface. U.S. 2011/0015496describes the use of a mobile communication device for real-time patientdata acquisition. No emphasis is placed on optimizing the user interfaceof the mobile device for its intended use. In U.S. 2011/0306859 amultipurpose, modular platform for mobile medical instrumentation isdescribed including the use of a cell phone or tablet computer forreal-time patient data acquisition. Once again, no emphasis is placed onoptimizing the user interface of the mobile device for its intended use.

SUMMARY OF THE INVENTION

Graphical layouts, algorithms, and methods are introduced herein toimplement new user interfaces for mobile and/or wearable medicaldevices. In one aspect of the present invention, graphical layouts areintroduced for simplified presentation of time-dependent patient data.In another aspect of the invention, methods and algorithms areintroduced to acquire, extract and present relevant features of patientdata real-time in order to simplify the graphical presentation andinterpretation. In another aspect of the invention, elements of amulti-modal user interface are introduced in order to simplify andminimize the user's interaction with the medical wearable device. In yetanother aspect of the invention, further methods are introduced forreal-time interaction between a user or several users and a wearable orseveral wearable medical devices. In one embodiment of the presentinvention, a smartphone, a smart watch, a head-mounted device or similardevices can be used to acquire and display in real-time patient data,e.g., electrocardiogram and relevant features, e.g., heart rate, etc. Inanother embodiment of the present invention, smartphones, smart watches,head-mounted devices or similar devices can be used to share inreal-time the patient data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: Methods of extracting relevant features from patient data inreal-time according to the present invention.

FIG. 2: Displaying time-dependent patient data using a simplified timecoordinate according to the present invention.

FIG. 3: One simplified display of relevant features of patient dataaccording to the present invention.

FIG. 4: Another simplified display of relevant features of patient dataaccording to the present invention.

FIG. 5: Some algorithms used to support relevant feature extraction frompatient data according to the present invention.

FIG. 6: Simplified user interface showing changes in relevant patientdata features and tracking history of such changes according to thepresent invention.

FIG. 7: Using the user interface according to the present invention forcatheter guidance.

FIG. 8: Simplified user interface showing both time-dependent patientdata and relevant features according to the present invention.

FIG. 9: Simplified user interface showing time-dependent patient data inreal time and frozen as reference according to the present invention.

FIG. 10: Elements of a user interface and methods for user interactionaccording to the present invention.

FIG. 11: Simplified user interface for a head-mounted device accordingto the present invention.

FIG. 12: Head-mounted device and methods for user interaction accordingto the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a method for the extraction of relevant features frompatient data in real-time according to the present invention. In oneembodiment of the present invention, the graph 100 illustrates asequence of 5 periods (t₀ through t₄) of a biological signal representedin the coordinate system Amplitude-Time (A-t). Such a signal canrepresent, for example, electrocardiogram (ECG), plethysmogram, pulseoximetry, blood pressure, etc. One of the characteristics of such signalis that it has a certain periodicity corresponding to the periodicity ofbody functions.

In one embodiment of the present invention, periodical signals areconsidered for feature extraction. In another embodiment of the presentinvention, signals are considered which are not periodical and happen atirregular time intervals. Traditionally, the variations in the amplitudeof a signal are displayed on a time axis as illustrated by graph 100.For example, in Graph 100, a signal or waveform period 101 isillustrated starting at the moment t₀ and ending at moment t₁, followedby signal period 102 starting at t₁ and ending at t₂, period 103starting at t₂ and ending at t₃, period 104 starting at t₃ and ending att₄, and period 105 starting at t₄ and ending at t_(S). One of thebenefits of such a display (100) is that it allows for trend analysis,i.e., the user can follow the history of amplitude changes. Onedisadvantage of such display on a time axis is that it requires arelatively large real estate to be used for the display, e.g., a largescreen or long print-outs in order to display a large enough number ofsignal periods. The amount of signal data increases even more in thecase of patient monitoring, when such signals must be monitored andpotentially recorded over long periods of time, i.e., days and weeks.

By observing the sequence of waveforms in Graph 100, one can notice thateach period can be analyzed and certain relevant features extracted foreach such period. In one embodiment of the present invention, FIG. 1,130 illustrates certain relevant features which can be extracted fromthe signal sequence in Graph 100. It should be obvious for somebodyskilled in the art that the illustrations in FIG. 1, 130 are notlimitations of the present inventions and that other relevant featurescan be extracted from the signal in both time and frequency domainsbased on the same principles and with the same goals as described by thepresent inventions. It should further be obvious for somebody skilled inthe art that a signal period can be divided into any number of relevantsegments as well as any number of signal periods can be grouped into onesegment of interest.

FIG. 1, 130 illustrates several relevant features of the periodicbiological signal from Graph 100: a) the segments of interest 142, 145,and 146; b) the amplitude of interests 135 in segment 145, i.e., themaximum value of the signal in segment 145; the amplitudes of interest137 and 140 in segment 142, i.e., the maximum and respectively theminimum values of the signal in segment 142; the average value of thesignal 148 in segment 146.

The amplitudes of interest 135, 137, and 140 and the average value ofthe signal 148 can be determined in a number of ways as illustrated inthe present invention. It should be obvious to somebody skilled in theart that such ways are not limitations of the present invention and thatother ways to determine the amplitude of interest can be easilydetermined. In one embodiment of the present invention, the amplitude135 is determined as the largest amplitude within a signal period.

In another embodiment of the present invention, the amplitude 135 isdetermined as the largest amplitude within a certain period of timeafter a steep increase in the signal as determined by computing thesignal's first derivative or slope. In one embodiment of the presentinvention, amplitude 137 is calculate as the largest amplitude of thesignal segment 142 and amplitude 140 is calculated as the smallestamplitude of the signal segment 142.

In another embodiment of the present invention, an average value 148 ofthe segment 146 is calculated and subtracted from the signal values insegments 142 and 145. In such an embodiment, the amplitude 135 iscalculated as the largest positive value of segment 145, the amplitude137 is calculated as the largest positive amplitude of segment 142 andthe amplitude 140 is calculated as the largest negative amplitude ofsegment 142.

In one embodiment of the present invention, the average value 148 ofsegment 146 is calculated using equation 540 in FIG. 5.

The segments of interest 142, 145, and 146 can be determined in a numberof ways as illustrated in the present invention. It should be obvious tosomebody skilled in the art that such ways are not limitations of thepresent invention and that other ways to determine the segments ofinterest can be easily described. In one embodiment of the presentinvention, segment 145 is determined as being of a certain time lengtharound the maximum amplitude 135 determined as described above herein.In one embodiment of the present invention, the determination of thestart, end, and duration of segment 145 is made based on knownphysiological behavior generating the patient data/signal. For example,in the case of the signal being an ECG signal and the maximum amplitude135 being an R-peak, the typical start, end and duration of segment 145are determined by the activity of the atrio-ventricular node and aredocumented in the literature.

In one embodiment of the present invention, segment 146 is identified asthe period of time with no or little activity of the signal, i.e., theperiod of time in which the amplitude of the signal is constant orquasi-constant. In one embodiment of the present invention, equation 510in FIG. 5 is used to compute the signal variance and to determine thepresence or lack of activity if the variance goes above or stays below acertain threshold, respectively.

In another embodiment of the present invention, the lack of activity insegment 146 is determined if the differences between the largest and thesmallest of the amplitudes of consecutive or quasi-consecutive samplesremain below a certain threshold.

In one embodiment of the present invention, the determination of thestart, end, and duration of segment 142 is determined from knownphysiological behavior generating the patient data/signal. For example,in the case of the signal being an ECG signal and the maximum amplitude135 being an R-peak, the typical start, end and duration of segment 142are determined by the activity of the sino-atrial node and aredocumented in the literature as the P-segment and the P-wave. In anotherembodiment of the present invention, segment 142 and 145 are adjacent.Segment 142 ends and segment 145 starts at or at a certain time intervalbefore the signal reaches its minimum amplitude value between the momentwhen it reaches amplitude 137 and the moment when it reaches amplitude135.

A signal period, e.g. periods 101 through 105 can be identified innumber of ways as illustrated in the present invention. It should beobvious to somebody skilled in the art that such ways are notlimitations of the present invention and that other ways to determinethe signal period can be easily determined.

In one embodiment of the present invention, a signal period isconsidered to start when the slope of the signal curve calculated as thesignal's first derivative surpasses a certain threshold. The signalperiod is considered to stop when the subsequent signal period starts.In another embodiment of the present invention, a signal period isconsidered to start when the amplitude 135 is detected and last untilthe next (subsequent) amplitude 135 is detected. The duration of thesignal period is measured in seconds and is computed by dividing thenumber of signal samples of the signal period by the sampling rate.

The method of extraction of relevant features from patient data asillustrated herein is not a limitation of the present invention. Itshould be obvious to somebody skilled in the art that other methods forfeature extraction can be applied with a twofold purpose: a) to minimizethe amount of information needed to be presented to the user and b) tominimize and/or simplify the presentation of time-dependent data. Suchfeature extraction methods can be morphological, statistical, andcomputational and other artificial intelligence methods, includingadaptive and auto-adaptive methods, obvious to somebody skilled in theart. They can be applied in the time domain, in the frequency domain(using the Fourier Transform), or in another domain obtained by datatransformation, e.g. principal component analysis (using theKarhunen-Loeve Transform). The relevant feature extraction according tothe present invention does act as a practical data compression andprincipal components analysis algorithm, i.e., instead of having tointerpret the entire sequence of patient data, one can interpret onlythe relevant features extracted. Thus, the system display and theuser/system interaction can be simplified as described herein.

In one embodiment of the present invention, morphological or descriptivemethods are used for feature extraction including: maximum and minimumsignal amplitudes, signal slopes, presence or lack of signal changes,sequence of certain signal elements like amplitudes, segments, andslopes, identification of signal segments based of specific segmentcharacteristics. In another embodiment of the present invention,statistical features are extracted from the signal including statisticalmoments of first and second order, e.g., a) average signal values over asignal segment, over a signal period or over multiple signal segmentsand periods, e.g., computed according to FIG. 5, 540; b) signal varianceover a signal period or over multiple signal segments and periods, e.g.,computed according to FIG. 5, 510; c) signal correlation over a signalperiod or over multiple signal segments and periods, e.g., computedaccording to FIG. 5, 520.

In another embodiment of the present invention, new features arecalculated based on extracted features from the data, as for example,illustrated in FIG. 5 by 530, whereby A_(M) may correspond to amplitude135, P_(M+) may correspond to amplitude 137, P_(M−) may correspond toamplitude 140, and T_(M) may correspond to amplitude 148 or to anotheramplitude of interest of another segment of interest in the signalperiod. The changes in relevant features extracted from the signal fromperiod to signal period and over longer periods of time can be displayedin a simplified manner according to the present invention as shownfurther herein.

For example, in one embodiment of the present invention, the values ofthe signal variance in segment 142 can be displayed and certain changesin the signal variance can be interpreted to reflect medical conditionsor specific data acquisition locations in the body. In anotherembodiment of the present invention, the computed feature according to530 in FIG. 5 may be displayed in a simplified manner as illustrated inFIG. 8.

Correspondingly, Graph 100 can be redrawn as illustrated by Graphs 150through 154, signal period by signal period by taking into account therelevant features illustrated by Graph 130. Graph 150 corresponds to thesignal period starting at t₀ with its two relevant segments 166 and 168and its relevant amplitude 167 for segment 166 and amplitude 169 forsegment 168. Similarly, Graph 151 corresponds to the signal periodstarting at t₁ with its two relevant segments 171 and 173 and itsrelevant amplitude 172 for segment 171 and amplitude 174 for segment173. Graph 152 corresponds to the signal period starting at t₂ with itstwo relevant segments 176 and 180 and its relevant amplitude 178 and 177for segment 176 and amplitude 179 for segment 180. Graph 153 correspondsto the signal period starting at t₃ with its two relevant segments 181and 183 and its relevant amplitude 182 for segment 181 and amplitude 184for segment 183. And Graph 154, which corresponds to the signal periodstarting at t₄ with its two relevant segments 185 and 189 and itsrelevant amplitude 186 and 187 for segment 185 and amplitudes 188 and190 for segment 189.

According to the present invention, graphs 150 through 154 do not needto be displayed at the same time on the same screen but can be displayedone after another on the screen. Tus, a smaller screen can be used todisplay the data from sequence of Graphs 150-154 instead of using Graph100. Second, by extracting the relevant features from the patient datain Graph 100 as illustrated by Graph 130, according to the presentinvention, only the relevant segments and amplitudes need to bedisplayed and not all the patient data in Graph 100. Thus, according tothe present invention, a smaller screen can be used to display the databy displaying only the relevant features instead of all the data. As aresult, according to the present invention, a) the original sequence ofpatient data (signal) was compressed, i.e. reduced to a lesser number ofrelevant elements and b) the time-dependency of the patient data can bedisplayed in a simplified way in order to allow for the use of a smallerlayout and screen real estate.

FIG. 2 illustrates displaying time-dependent patient data using asimplified time coordinate according to the present invention. TheGraphs 150 through 154 from FIG. 1 are superimposed on the same Graph200. In one embodiment of the present invention, graphs 150 through 154are aligned at a fix point on the display. In one embodiment of theinvention, the maximum amplitude 135 in FIG. 1 is used to align thesegraphs by always displaying the time of the amplitude 135 at the samelocation (abscissa) on the screen.

In one embodiment of the present invention, superimposing graphs on thesame screen as illustrated by FIG. 2 also corresponds to the history ofthe signal periods, i.e., the graphs corresponding to each signal periodare superimposed one behind the other in the order of their temporalmoments with the most recent signal period in front. Any number ofsignal periods from Graph 100 in FIG. 1 can be transformed intoindividual graphs as illustrated by Graphs 150 through 154 in FIG. 1 andthen superimposed on the same graph as illustrated by Graph 200 in FIG.2. The Graph 200 illustrates two relevant signal segments 220 and 210 asthey have been identified in Graphs 150 (166 and 168) through 154 (185and 189). The corresponding signals and relevant features illustrated inGraphs 150 through 154 from FIG. 1 are superimposed on Graph 200. Thesignal at time moments t₀ through t₄ are represented by 225 in segment220 and by 215 in segment 210. The relevant amplitudes are representedby 227 and 228 in segment 220 and by 217 in segment 210.

In one embodiment of the present invention, the most recent signalcorresponding to signal period at moment t₄ is represented by a fullline while the waveforms corresponding to signal periods at priormoments t₀ through t₃ are represented by dotted lines (222 in segment220 and 212 in segment 210). Any number of signal periods at any numberof moments can be superimposed on the same Graph illustrated by 200.

In another embodiment of the present invention, the waveformscorresponding to different signal periods at different moments in timeare represented by different colors. In another embodiment of thepresent invention, the waveforms at more recent moments are presented inbrighter (higher intensity) colors while the waveforms at past momentsare represented with fading colors such that the most recent waveformhas the brightest color. In another embodiment of the present invention,the different waveforms at different moments are represented usingdifferent shades of gray. The purpose of this display layout is toemphasize the display on the same display area of the relevant featuresat the current moment in time, e.g., relevant amplitudes while showingat the same time some history of the waveforms at some previous momentsin time.

In one embodiment of the present invention, the Graph displayed in FIG.2 is updated with every new signal period showing the most recent andseveral past most recent relevant features and waveforms.

FIG. 3 illustrates one simplified display of patient data according tothe present invention. In display 300 only the relevant featuresextracted from patient data are displayed. In one embodiment of thepresent invention, relevant amplitudes are displayed for two segments ofinterest 302 and 304. In one embodiment of the present invention, theamplitudes at the current moment in time are displayed as full dots, 340and 345 for segment 304 and 350 for segment 302 respectively. In oneembodiment of the present invention, the amplitudes at two previousmoments in time are displayed as dotted circles 370 for segment 304 and375 for segment 302.

In one embodiment of the present invention, the dotted line 310identifies the amplitude of interest 217 from FIG. 2 or amplitude 135from FIG. 1. In one embodiment of the present invention, the dotted line320 identifies the amplitude of interest 227 in FIG. 2 or 137 in FIG. 1and the dotted line 330 identifies the amplitude of interest 228 in FIG.2 or 140 in FIG. 1. In one embodiment of the present invention, thegraph displayed in FIG. 3 is updated with every new signal period andshows the most recent and several past most recent relevant features.

In one embodiment of the present invention, the levels 355 and 360represent the average value 148 from FIG. 1. In another embodiment ofthe present invention, the levels 355 and 360 represent anotherreference value, e.g., the value zero.

FIG. 4 illustrates another simplified display of relevant features ofpatient data according to the present invention. The Graph 400 in FIG. 4does not show any more the relevant data segments identified by 130 inFIG. 1.

In one embodiment of the present invention, Graph 400 displays only therelevant features as intensity bars. In one embodiment of the presentinvention, intensity bar 410 represents the amplitude of interest 217from FIG. 2, intensity bar 420 represents the amplitude of interest 227from FIG. 2 and intensity bar 430 represents the amplitude of interest228 from FIG. 2.

In another embodiment of the present invention, an intensity barrepresents the value computed according to equation 530 in FIG. 5.

In another embodiment of the present invention, intensity bars representthe value computed according to equations 510 and or 520 in FIG. 5. Inone embodiment of the present invention, the level of the intensity barcorresponds to the most current value of the relevant feature, value 450for feature represented by the bar 410, value 445 for the featurerepresented by the bar 420 and value 440 for the feature represented bythe bar 430.

In one embodiment of the present invention, the level 460 represents theaverage value 148 from FIG. 1. In another embodiment of the presentinvention, the level 460 represents another reference value, e.g., thevalue zero. In one embodiment of the present invention, markers are usedto indicate the maximum maximorum value attained by relevant features intime, e.g., marker 470 for feature 410, marker 475 for feature 420. Inone embodiment of the present invention, marker 465 indicates theminimum minimorum value attained by feature 430.

In one embodiment of the present invention, the intensity bars and themaximum maximorum and minimum minimorum values displayed in FIG. 4 areupdated with every new signal period.

FIG. 5 illustrates algorithms used to support relevant featureextraction from patient data according to the present invention. In oneembodiment of the present Invention, the standard deviation of thesignal Sxj is computed according to 510, whereby n represents the numbern of data samples x_(i) for the j-th signal period, i=1,n. The value ⁻xrepresents the average value of the data samples over the j-th signalperiod 540. The standard deviation computed according to 510 is ameasure of the variations of the signal values around its average valueduring a signal period.

In one embodiment of the present invention, the auto-correlationcoefficient Cx_(j,j-1) is computed according to 520 for the signal x atthe j-th signal period and at the previous j−1 signal period, whereby nrepresents the number of data samples x_(i) for the j-th signal period,i=1,n. The value ^(−x) _(j) represents the average value of the datasamples over the j-th signal period computed according to 540. The value−x_(j−1) represents the average value of the data samples computedaccording to 540 over the j-1-th signal period, i.e., of the one signalperiod before the j-th heart cycle. Sx_(j) is the standard deviation ofthe signal computed according to 510 for the j-th signal period.Sx_(j−1) is the standard deviation of the signal computed according to510 for the j-1-th signal period. In general, the number of samples nfor the j-th signal period is different than the number of samples forthe j-1-th signal period.

According to the present invention, n samples are considered for thecalculation of both Sx_(j) and Sx_(j−1), whereby n is the number ofsamples of the j-th signal period. In another embodiment of theinvention, the auto-correlation coefficient can be calculated using 520as Cx_(j,k), whereby j and k are any two signal periods. This includesthe situation in which j=k and the coefficient is calculated for thesame signal period.

In one embodiment of the present invention, the auto-correlationcoefficient 520 is used to filter out signal periods very different fromone another. It is assumed that, under normal conditions, the signalperiods have a certain degree of similarity to each other. In thepresence of noise or other artifacts or in case of malfunctions, thesignal periods may be very different from one another. Theauto-correlation coefficient 520 is used to estimate the degree ofsimilarity between signal periods. A higher auto-correlation coefficientindicates a higher degree of similarity between two signal periods thana lower auto-correlation coefficient. Thus, if the auto-correlationcoefficient of two signal periods is below a certain threshold, it canbe considered that the two signal periods are weakly correlated oruncorrelated. In such a case, which may occur, for example, due toelectromagnetic interference, the two signal periods are excluded fromthe computation of relevant features. With other words, according to thepresent invention, only signal periods which have a reasonable degree ofsimilarity are considered for the extraction of relevant features.

In one embodiment of the present invention, one relevant featurecomputed from the signal is the sum Σ_(M) of maximum relevant amplitudesof the signal for each signal period. In one embodiment of the presentinvention, the sum Σ_(M) is calculated according to equation 530 in FIG.5, whereby A_(M) is the maximum amplitude of the signal in the segmentof interest 145 in FIG. 1, P_(M+) is the maximum positive amplitude ofthe signal aligned with the segment of interest 142 in FIG. 1, P_(M−) isthe maximum negative amplitude of the signal aligned with the segment ofinterest 142 in FIG. 1, and T_(M) is the maximum amplitude of the signalaligned to another segment of interest of the signal period, for examplewith the segment 146 in FIG. 1.

In another embodiment of the present Invention, the sum Σ_(M) iscalculated as: Σ_(M)=A_(M)+P_(M+)+P_(M−).

In another embodiment of the present invention, T_(M) is the averagevalue of the signal in segment 146 in FIG. 1 and the value Σ_(M) iscalculated as: Σ_(M)=A_(M)+P_(M+)+P_(M−)−T_(M).

In one embodiment of the present invention, the parameters in FIG. 5,i.e., the standard deviation 510, the auto-correlation 520, the sum ofrelevant amplitudes 530, and the average value 540 are computed for asignal period. In another embodiment of the present invention, theparameters in FIG. 5 are computed for several consecutive signalperiods. In another embodiment of the present invention, the parametersin FIG. 5 are computed for a fraction of a signal period, e.g., only foran interval/segment of interest within a signal period.

FIG. 6 illustrates a simplified user interface showing changes inrelevant features and tracking history of such changes according to thepresent invention. Values of a relevant feature are represented on theaxis 620. Such a relevant feature can be any of the relevant featuresextracted from the patient data as described herein.

In one embodiment of the present invention, a relevant feature may be anamplitude of interest.

In another embodiment, a relevant feature may be the sum computedaccording to 530 in FIG. 5.

In one embodiment of the present invention only one relevant feature isdisplayed as illustrated by display 600.

In another embodiment of the present invention, several relevantfeatures are displayed at the same time on a same screen using onedisplay 600 for each of the relevant features. The level 630 illustratesthe reference level of the values of the relevant feature. The icon 605representing a warning sign is displayed whenever an issue is detectedregarding the computation of the value of the relevant feature. In oneembodiment of the present invention, a warning sign may be displayed ifthe auto-correlation coefficient calculated according to 520 in FIG. 5decreases below a certain threshold. The warning sign can be displayedin different ways in different embodiments of the present invention.

In one embodiment of the present invention, an audible warning signal isalso generated when a warning signal is displayed. The marker 610represents the lower acceptable limit of the value range for the valuesof the relevant feature and the marker 615 represents the upperacceptable limit of the value range. In one embodiment of the presentinvention, the corresponding marker changes appearance whenever thevalue of the relevant feature is less than the lower limit or largerthan the upper limit, in order to indicate that the value of therelevant feature is outside the acceptable range.

In one embodiment of the present invention markers 610 and 615 turnyellow whenever the value of the relevant feature is less than the lowerlimit 610 or larger than the upper limit 615. A graphical warning signalmay be displayed and/or an audible warning signal may be generatedaccording to the present invention whenever the value of the relevantfeature is outside the acceptable range. The markers 640 and 650 arehistory markers. Marker 640 represents the minimum value within theacceptable range, i.e., within the limits 610 to 615, which the relevantfeature has attained during a certain period of time, i.e., the minimumminimorum value. Correspondingly, marker 650 represents the maximumvalue within the acceptable range, i.e., within the limits 610 to 615,which the relevant feature has attained during a certain period of time,i.e., the maximum maximorum value.

In one embodiment of the present invention, the purpose of the markers660 and 670 is twofold. On one hand, a marker 660 or 670 shows thecurrent value of the relevant feature on the axis 620. On the otherhand, a marker 660 or 670 shows the direction/trend of the change of thevalue since the last display.

In one embodiment of the present invention, if the current value of therelevant feature is larger than the previous value, then the marker 660pointing upwards is displayed at the level of the current value on axis620. If the current value of the relevant feature is smaller than theprevious value then the marker 670 pointing downwards is displayed atthe level of the current value on axis 620. In another embodiment of thepresent invention, only the current value of the relevant feature isdisplayed on the axis 620 without the display of the change/trend.

In another embodiment of the present invention, the trend analysis ofthe values of the relevant features takes into account filtering andaveraging to allow for a more accurate determination of the trend thanby only considering the difference between the current and the previousvalues of the relevant feature.

FIG. 7 illustrates one embodiment of the present invention applied tocatheter guidance using the electrical conduction system of the heartand one control electrode placed over the manubrium of the sternum.

In the embodiment of the present invention illustrated in FIG. 7, thesignal illustrated in FIG. 1 is a navigation signal computed from theintravascular ECG signal at the tip of the catheter and the skin ECGsignal at the control electrode.

In this embodiment, the segment of interest 142 identified in FIG. 1 isaligned with the P-segment of the patient's ECG waveform, the segment145 identified in FIG. 1 is aligned with the QRS complex of thepatient's ECG waveform, and the segment 146 identified in FIG. 1 isaligned with the baseline segment of the patient's ECG waveform betweenthe T and P segments. The relevant feature displayed on axis 730 ofdisplay 700 is the sum Σ_(M) calculated as Σ_(M)=A_(M)+P_(M+)+P_(M−),whereby A_(M) is the maximum amplitude of the navigation signal in thesegment of interest aligned with the QRS complex of the ECG waveform,P_(M+) is the maximum positive amplitude of the navigation signalaligned with the P-segment of the ECG waveform, and P_(M−) is themaximum negative amplitude of the navigation signal aligned with theP-segment of the ECG waveform.

In one embodiment of the present invention, the reference level 720represents the value of Σ_(M) when the tip of the catheter is closest tothe control electrode.

In another embodiment of the present invention, the reference level 720represents the average value 148 of segment 146 in FIG. 1, i.e., theaverage value of the ECG baseline.

In yet another embodiment of the present invention, the reference level720 has the value zero, which means that values below the referencelevel 720 are negative and values above the reference level 720 arepositive. The display 715 displays the heart rate in beats per minutecomputed from the ECG signal period determined from the ECG signal atthe control electrode with one of the methods described in FIG. 1. Thesignal period is measured in seconds and the heart rate in beats perminute is computed as one over the signal period and divided by 60.

In one embodiment of the present invention, the heart rate is calculatedfor each new signal period.

In another embodiment of the present invention, the heart rate iscalculated as an average value over several signal periods and afterexclusion of the uncorrelated signal periods based on theauto-correlation criterion described in FIG. 5.

In one embodiment of the present invention, the icon 710 represents awarning sign displayed whenever an issue is detected regarding thecomputation of Σ_(M).

In one embodiment of the present invention, the warning sign isdisplayed if the auto-correlation coefficient calculated according to520 in FIG. 5 decreases below a certain threshold. The warning sign canbe displayed in different ways in different embodiments of the presentinvention. In one embodiment of the present invention, an audiblewarning signal is also generated when a warning signal 710 is displayed.

In one embodiment of the present invention, the icon 705 illustrates aheart on which the cavo-atrial junction is visibly marked. The locationof icon 705 on the display 700 at the top of the axis 730 signifies thefact that, the closer the value displayed on the axis is to the icon,the closer the catheter tip is to the cavo-atrial junction.

In one embodiment of the present invention, icon 725 illustrates therelative location on the axis 730 of values of the navigation signalcorresponding to the tip of the catheter in the proximity of the controlelectrode. With other words, whenever the value Σ_(M) shown on axis 730is close to icon 725, then the tip of the catheter is close to thecontrol electrode.

In one embodiment of the present invention, the marker 725 turns bluewhenever the value Σ_(M) shown on axis 730 is close to the referencelevel 720. In one embodiment of the present invention, a symbol isrepresented in the color blue indicating the reference level 720. Themarker 735 indicates the lowest acceptable value Σ_(M) which can bedisplayed without distortions and the marker 740 indicates the highestacceptable value Σ_(M) which can be displayed without distortions. Allvalues of Σ_(M) higher than the marker 740 are represented at the levelof marker 740 and all values of Σ_(M) lower than the marker 735 arerepresented at the level of marker 735 on the axis 730. Such situationscan happen, for example in the case of inappropriate selection of signalscale and in case of electromagnetic interferences. In such situations,a warning signal 710 is displayed and the user can correct the situationby selecting an appropriate signal scale or eliminating the cause ofelectromagnetic interference.

In one embodiment of the present invention, a warning signal 710 is alsodisplayed if the auto-correlation coefficient 520 in FIG. 5 is below acertain threshold. The marker 745 represents the minimum minimorum valueof Σ_(M) recorded during the course of a catheter placement procedureand the marker 750 represents the maximum maximorum value of Σ_(M)recorded during the course of a catheter placement procedure.

In one embodiment of the present invention, initially, i.e., in thebeginning of the catheter placement procedure, the values represented by745 and 750 are zero. For each signal period, a current positive valueof Σ_(M) is compared with the value represented by 750. If the currentvalue of Σ_(M) is larger than the value represented by 750 then thevalue represented by 750 is updated with the current value of Σ_(M).Thus the value 750 always represents the largest attained value ofΣ_(M). Similarly, for each signal period, a current negative value ofΣ_(M) is compared with the value represented by 745. If the currentvalue of Σ_(M) is smaller than the value represented by 745 then thevalue represented by 745 is updated with the current value of Σ_(M).Thus, 745 always represents the smallest (or the largest negative)attained value of Σ_(M).

In one embodiment of the present invention, the value of Σ_(M) isrepresented on the axis 730 as either an upwards pointing arrow asillustrated by 755 or a downwards pointing arrow as illustrated by 760.The horizontal line of the icons 755 and 760 represent the current valueof Σ_(M) on the axis 730. The arrow of icons 755 and 760 represent thetrend in the change of the value, either from the last update or duringa certain period of time. If the arrow points upwards as illustrated byicon 755, then the current value of Σ_(M) represents an increase invalue compared to a previous value or average value or trend of valuechange. If the arrow points downwards as illustrated by icon 760, thenthe current value Σ_(M) represents a decrease in value compared to aprevious value or average value or trend of value change.

In one embodiment of the present invention, the markers 755 and 750 aredisplayed in green in order to indicate a desired trend in the valuesdisplayed on axis 730. In one embodiment of the present invention, themarkers 760 and 745 are displayed in red in order to indicate anundesired trend in the values displayed on axis 730.

In one embodiment of the present invention markers 740 and 735 turn toyellow whenever the value of the relevant feature is less than the lowerlimit 735 or larger than the upper limit 740 in order to indicate awarning condition.

In one embodiment of the present invention, audible signals or sequencesof audible signals of different frequencies and intensities aregenerated when any of the markers 725, 735, 740, 745, 750, 755 or 760changes colors.

FIG. 8 illustrates a simplified user interface showing bothtime-dependent patient data and the display of relevant featuresaccording to the present invention.

In one embodiment of the present invention, the display 800 contains thefollowing elements: a) a display 810 of a relevant feature usingintensity bars as illustrated in FIG. 4; b) a display 820 of patientsignals in the simplified format illustrated in FIG. 2; c) a display 830of a relevant feature showing value tracking and display history asillustrated in FIG. 6; d) a numerical display of patient information 840as illustrated in FIG. 7; and a warning signal 850 as illustrated inFIGS. 6 and 7.

In one embodiment of the present invention, the elements 810, 820, and830 of the display 800 represent the same relevant feature.

In another embodiment of the present invention, the elements 810, 820,and 830 of the display 800 represent different relevant features, e.g.,the display 820 represents the patient's ECG waveforms and theirrelevant amplitudes, display 830 represents the relevant feature Σ_(M)as described in FIG. 7, the intensity bar 810 displays the patient'soxygen saturation, the field 840 displays the heart rate and the warningsignal 850 relates to thresholds of the patient's blood pressure. Thedisplay 800 is not a limitation of the present invention and it shouldbe obvious to somebody skilled in the art that other displayconfigurations are possible showing one or several or additional displayelements as illustrated in FIG. 8. It should be further obvious tosomebody skilled in the art that the display elements of the display 800can refer to different types of patient information than those describedherein.

FIG. 9 illustrates a simplified user interface showing time-dependentpatient data in real time and frozen patient data for referenceaccording to the present invention. In certain clinical situations it isneeded that the user can compare the currently displayed patient datawith patient data displayed at a previous moment in time.

In one embodiment of the present invention, on display 900 in FIG. 9,real time data 910 is displayed in a similar manner as in FIG. 2. Frozendata at a previous moment in time is displayed by 920.

In one embodiment of the present invention, only the most recent signalperiod represented by a full line in display 910 is frozen for displayby the display 920. In one embodiment of the present invention, the icon930 has a twofold purpose. On a touch screen, the icon 930 serves as aFreeze button. Whenever the user taps on the icon 930, the current datadisplayed by 910 is copied to the display 920. The display 920 remainsunchanged until the next time the user touches the icon 930 and new datais copied from display 910 to display 920. Icon 930 serves also toindicate to the user that the data in display 920 is frozen, i.e., ithas been acquired at a previous moment in time.

In one embodiment of the present invention, double tapping on the icon930 clears the display 920. In one embodiment of the present invention,the Freeze function illustrated in FIG. 9 can be achieved by voicecontrol. By pronouncing the word “Freeze”, the user performs the sameaction as tapping on icon 930. By pronouncing the word ‘Clear”, the userclears the display 920. In another embodiment of the present invention,the Freeze function illustrated in FIG. 9 can be implemented with anydisplay or combination of displays and data as, for example, thoseillustrated in FIG. 8. The illustrations in FIG. 9 are not limitationsof the current invention. It should be obvious to somebody skilled inthe art that other types of data and patient information can bepresented as a duality of real-time and frozen displays, whereas othericons and voice commands can be used to freeze data and clear thedisplay.

FIG. 10 illustrates elements of a user interface and methods for userinteraction according to the present invention.

In one embodiment of the present invention, the display 1000 illustratesseveral display and control elements.

In one embodiment of the present invention the display 1000 is also atouch screen. In one embodiment of the present invention, relevantfeatures of patient data 1070 are displayed as illustrated in FIG. 7.

In another embodiment of the present invention, relevant features ofpatient data are displayed as illustrated in FIG. 8. Relevant patientinformation may also be displayed as an alphanumeric field 1025. Icons,illustrated by 1060, may be displayed indicating the significance of therelevant features of interest displayed by 1070. A warning signal 1030may be displayed as illustrated in FIGS. 6 and 7.

By using the touchscreen function of the display 1000, in one embodimentof the present invention, a method to scroll the reference level of 1070up and down on the screen, for example swiping using one finger, isillustrated by 1050.

By using the touchscreen function of the display 1000, in one embodimentof the present invention, a method to increase and decrease the scalefor the display 1070, for example using two fingers, is illustrated by1052.

By using the touchscreen function of the display 1000, in one embodimentof the present invention, a method to increase and decrease the displayupdate speed (or scroll speed) of display 1070, for example using twofingers, is illustrated by 1054.

In one embodiment of the present invention, by using the resettouchscreen button 1048, the user can reset to zero the values of theminimum minimorum and maximum maximorum markers of the display 1070.

In one embodiment of the present invention, several touchscreen iconsare used to navigate different menus and screens of the user interface.Touching or tapping on icon 1046 navigates to the home screen, which inone embodiment of the invention is the display 1000. Touching or tappingon icon 1044 goes back one step in the navigation path. Touching ortapping on icon 1042 leads to a menu for settings. Touching or tappingon icon 1040 leads to a list of available menus, including a patientinformation menu.

In one embodiment of the present invention, touch icon 1005 allows theuser to make a phone call while looking at the display 1000. In oneembodiment of the present invention, when the user makes a phone callwhile displaying display 1000, the entire display or only the relevantfeature display 1070 are duplicated on the screen of the receivingphone.

In one embodiment of the present invention, the user can receive andpick up a phone call while displaying display 1000 and the entiredisplay or only the relevant feature 1070 are duplicated on the screenof the calling phone.

In one embodiment of the present invention, button 1020 providesadditional methods for the interaction of the user with the device.

In one embodiment of the present invention, by rotating the button 1020clockwise or counterclockwise, the user can increase or respectivelydecrease the scale of the display 1070. By pulling the button 1020 andthen rotating it, the user can scroll up and down the reference level ofdisplay 1070. By pressing the button 1020, the user can reset to zerothe minimum minimorum and the maximum maximorum values of display 1070.It should be obvious to somebody skilled in the art that other methodsand relevant functionality can be implemented using one or severalbuttons like 1020.

In one embodiment of the present invention, icon 1007 illustrates aheadphone and is displayed on display 1000 when a headphone is availablefor user interaction, for example by connecting an external headphone tothe jack 1017.

In one embodiment of the present invention, the icon 1010 illustrates amicrophone and is displayed on display 1000 when a microphone isavailable for user interaction, for example by connecting an externalmicrophone to jack 1015.

In one embodiment of the present invention, if a microphone is availablefor interaction, a method for the user to interact with the display 1000is by voice control. In one embodiment of the present invention, theword “Up” increases the scale of display 1070, the word “Down” decreasesthe scale of the display 1070, and the word “Reset” resets to zero theminimum minimorum and maximum maximorum values of display 1070.

In one embodiment of the present invention, touch icon 1008 allows theuser to take a picture and or make a short movie while displayingdisplay 1000.

In one embodiment of the present invention, such a picture or movie aretransmitted to a receiving or calling phone if a phone call initiatedusing icon 1005 is in progress.

In one embodiment of the present invention, icon 1008 indicates when acamera is available for use with the display 1000. In the situation inwhich a camera is available for use, the user can use gestures as amethod to interact with the display 1000.

In one embodiment of the present invention, waving the hand in front ofthe camera resets to zero the minimum minimorum and maximum maximorumvalues of display 1070. In one embodiment of the present invention,holding two fingers in front of the camera increases the scale ofdisplay 1070 while holding one finger in front of the camera decreasesthe scale of display 1070. In one embodiment of the present invention,holding the hand in front of the camera sends the relevant display datato a printer, if a printer is connected, for example by Bluetooth.

In one embodiment of the present invention the display, the interactionelements, and the interaction methods illustrated in FIG. 10 can beimplemented using a cellphone.

In another embodiment of the present invention the display, theinteraction elements, and the interaction methods illustrated in FIG. 10can be implemented using a smart watch. In another embodiment of thepresent invention the display, the interaction elements, and theinteraction methods illustrated in FIG. 10 can be implemented using ahead-mounted display.

In another embodiment of the present invention the display, theinteraction elements, and the interaction methods illustrated in FIG. 10can be implemented using a Google glass.

In another embodiment of the present invention the display, theinteraction elements, and the interaction methods illustrated in FIG. 10can be implemented using other types of mobile and/or wearable devices.

The illustrations in FIG. 10 are not a limitation of the presentinvention. It should be obvious for somebody skilled in the art thatother interaction elements, other functions, and other interactionmethods can be implemented using the elements illustrated in FIG. 10.

FIG. 11 illustrates a simplified user interface for a head-mounteddevice according to the present invention.

In one embodiment of the present invention, the display 1100 is a color640×360 pixel display. In one embodiment of the present invention, themain display layout 1100 is divided into a left image or column for liveinformation 1110, a field 1120 for static information, e.g., for frozendata or images, footer for supplementary information 1130, a menu bar1140, and a status bar 1150.

In one embodiment of the present invention, the live information field1110 displays relevant features of patient data as illustrated in FIG.10, 1070.

In another embodiment of the present invention, the live informationfield 1110 displays relevant features of patient data are displayed asillustrated in FIG. 8.

In one embodiment of the present invention, the static field 1120displays frozen images and patient data as illustrated in FIG. 9, 920.

In one embodiment of the present invention, the footer 1130 foradditional information displays warning signs, time stamps, and otherrelevant information, e.g., the patient's heart rate as described inFIGS. 6 and 7.

In one embodiment of the present invention, the menu bar 1140 displaysitems as those described in FIG. 10, e.g., 1040, 1042, 1044 and 1048 andin FIG. 9, 930.

In one embodiment of the present invention, the status bar 1150 showsthe current set of data being displayed, progress information fordifferent user interactions, or other information related to systemstatus, e.g., Bluetooth communication. The illustrations in FIG. 11 arenot a limitation of the present invention. It should be obvious forsomebody skilled in the art that other screen layouts and the display ofother information and control elements are possible.

FIG. 12 illustrates a head-mounted device and methods for userinteraction according to the present invention. In one embodiment of thepresent invention, a head-mounted device 1200 contains a display orscreen 1210, a front video camera 1220, a microphone 1230, a headphone1240, a lateral video camera 1270, battery, processing unit, and othersensors 1250, and a touchpad 1260.

In one embodiment of the present invention the unit 1250 includes a 3axis gyroscope, a 3 axis accelerometer, an ambient light sensor, and aproximity sensor. In one embodiment of the present invention, thehead-mounted device in FIG. 12 is a Google glass.

In one embodiment of the present invention, other wireless devices areconnected to the head-mounted device, e.g., a Bluetooth printer, asmartphone, or a tablet.

In one embodiment of the present invention, the method of interactionbetween an operator and the head-mounted device is optimized for the useby a sterile operator, i.e., for an operator with sterile glovesoperating in a sterile filed who cannot touch the head-mounted device.

In such an embodiment all interaction between the operator and thehead-mounted device is based on voice, hand gestures, and headmovements.

In one embodiment of the present invention, the touchpad 1260 allows theuser to tap, to slide forward, backward, up, and down, and to swipe upand down. The user can scroll through items displayed on the screen bysliding one finger over the touchpad and select one item and by tappingon the desired item. If the user selects an item like the referencelevel of the display 1110, sliding up and down on the touchpad will movethe reference level up and down on the display. Swiping down on thetouchpad will go back to a previous screen. This action is similar to aback button as illustrated in FIG. 10, 1044.

In one embodiment of the present invention, tilting the head down willexit the application. Shaking the head left and right will move througha list of options displayed on the screen, e.g., like the oneillustrated in FIG. 11, 1140 and holding the hand in front of a camerawill select an item from that list.

In one embodiment of the present invention, waving the hand in front ofthe front or lateral camera will freeze an image as in FIG. 9 or willreset markers as in FIG. 10 depending on the display mode. Holding twofingers in front of the camera will increase the scale of the signaldisplayed by 1110 in FIG. 11 and holding one finger in front of thecamera will decrease the signal scale. If in data display mode, holdingthe hand in front of a camera will send the current data displayed onthe display to a connected device, e.g., to a printer, to a smartphoneor to a tablet.

In one embodiment of the present invention, the head-mounted device inFIG. 12 can be controlled by voice. The word “Up” increases the scale ofdisplay illustrated by 1110 in FIG. 11, the word “Down” decreases thescale of the display 10110, and the word “Reset” resets to zero theminimum minimorum and maximum maximorum values of display 1110. The word“Patient” changes the static display 1120 to a patient informationdisplay and the word “Data” changes it back to displaying relevant data.The word “Back” has similar effects like the back button 1044 in FIG.10. In one embodiment of the present invention, the head-mounted devicecan be taught new voice commands by initiating actions and associatingwords to them.

In one embodiment of the present invention, the headphone 1240 is usedfor audible warning signals generated as described herein, for examplein FIG. 10.

The illustrations in FIG. 12 are not a limitation of the presentinvention. It should be obvious for somebody skilled in the art thatother methods of interaction can be implemented using voice control,hand gestures, head movements and tapping and swiping on the touchpad.

What is claimed is:
 1. A method for simplifying a display of signals,the method comprising: obtaining an electrocardiogram (ECG) signal withan electrode located at a tip of a catheter inserted into a body of apatient; identifying an ECG waveform from the ECG signal; extracting aset of relevant features of the ECG signal from each segment of interestof a plurality of segments of interest of the ECG waveform at differenttime periods, wherein: each of the plurality of segments of interestcorresponds to a different time period, wherein each segment of interestcorresponds to a particular time period, wherein an amplitude axis isillustrated as a single vertical plane, and wherein a plurality ofvisual indicators are illustrated in the single vertical plane, and eachrelevant feature of the set of relevant features is displayed as avisual indicator on the amplitude axis and illustrates at least one of:(i) a maximum amplitude measured for each segment of interest, (ii) aminimum amplitude measured for each segment of interest, or (iii) anaverage value of the ECG waveform within each segment of interest; andgenerating a display screen that includes the set of relevant featuresof each of the plurality of segments of interest superimposed on theamplitude axis, wherein the display screen is configured to emphasizerelevant features of a most recent segment of interest of the pluralityof segments of interest.
 2. The method as defined in claim 1, whereinthe display screen is configured for display on a touchscreen, whereintouch, input via touchscreen, controls displaying the set of relevantfeatures.
 3. The method as defined in claim 1, wherein the set ofrelevant features on the display screen is auto-adaptive as a functionof information content of the ECG signal.
 4. The method as defined inclaim 1, wherein extracting the set of relevant features includesmorphological analysis of signal characteristics in time or frequencydomains.
 5. The method as defined in claim 1, wherein extracting the setof relevant features includes statistical analysis of signalcharacteristics in time or frequency domains.
 6. The method as definedin claim 1, wherein extracting the set of relevant features includes areduction or selection of a number of features characterizing the ECGsignal via a selective data compression.
 7. The method as defined inclaim 1, wherein extracting the set of relevant features includes adefinition and computation of the set of relevant features based on arelevance analysis.
 8. The method as defined in claim 7, wherein thedefinition and computation of the set of relevant features includes adefinition and computation of sum and differences of amplitudes of aplurality of ECG waveforms.
 9. The method as defined in claim 7, whereinthe computation of the set of relevant features includes a computationof a standard deviation and of a correlation coefficient.
 10. A methodfor displaying a location of a tip of an intravascular catheter, themethod comprising: obtaining an electrocardiogram (ECG) signal with anelectrode located at the tip of the intravascular catheter inserted intoa body of a patient; identifying an ECG waveform from the ECG signal;extracting signed values of peak values of a R-wave, a positive P-wave,and a negative P-wave of the ECG signal from each segment of interest ofa plurality of segments of interest of the ECG waveform at differenttime periods; computing a set of relevant features of the ECG waveformas a sum of extracted peak values; and generating a display screen thatincludes the set of relevant features of each of the plurality ofsegments of interest superimposed on an amplitude axis, wherein eachsegment of interest corresponds to a particular time period, wherein theamplitude axis is illustrated as a single vertical plane, wherein aplurality of visual indicators are illustrated in the single verticalplane, wherein the display screen is configured to emphasize therelevant features of a most recent segment of interest of the pluralityof segments of interest, wherein the display screen is updated in realtime with additional segments of interest, and wherein each relevantfeature of the set of relevant features of the ECG waveform is displayedas a visual indicator on the amplitude axis and illustrates at least oneof: (i) a maximum amplitude measured for each segment of interest, (ii)a minimum amplitude measured for each segment of interest, or (iii) anaverage value of the ECG waveform within each segment of interest. 11.The method as defined in claim 10, further comprising: responsive todetermining the location of the tip of the catheter is outside of apredefined location range within the body based on at least the set ofrelevant features, updating the display screen to include a warningicon.
 12. The method as defined in claim 10, further comprising:determining a trend of changes in the relevant features of one or moreof the most recent segment of interest or a previous segment ofinterest; and updating, in real-time, the display screen to include agraphical representation of the trend of changes in the relevantfeatures of one or more of the most recent segment of interest or aprevious segment of interest.
 13. The method as defined in claim 1,wherein each visual indicator is one of a dot or a dash.
 14. The methodas defined in claim 1, wherein each visual indicator represents asingular point in time.
 15. A method performed in connection with amobile medical device, comprising: obtaining an electrocardiogram (ECG)signal with an electrode located at a tip of a catheter inserted into abody of a patient; identifying an ECG waveform from the ECG signal;extracting a set of relevant features of the ECG signal from eachsegment of interest of a plurality of segments of interest of the ECGwaveform at different time periods, wherein: each of the plurality ofsegments of interest correspond to a different time period, wherein eachsegment of interest corresponds to a particular time period, wherein anamplitude axis is illustrated as a single vertical plane, and wherein aplurality of visual indicators are illustrated in the single verticalplane, and each relevant feature of the set of relevant features isdisplayed as a visual indicator on the amplitude axis and illustrates atleast one of: (i) a maximum amplitude measured for each segment ofinterest, (ii) a minimum amplitude measured for each segment ofinterest, and (iii) an average value of the ECG waveform within eachsegment of interest; and displaying one or more graphical elementsrepresenting the set of relevant features of each of the plurality ofsegments of interest superimposed on the amplitude axis on a displayscreen of the mobile medical device, wherein the display screen isconfigured to emphasize relevant features of a most recent segment ofinterest of the plurality of segments of interest.
 16. The method asdefined in claim 15, wherein the relevant features of the most recentsegment of interest are emphasized over the set of relevant features ofa previous segment of interest and are displayed without a timecoordinate.
 17. The method as defined in claim 15, wherein a history ofchanges over time of the relevant features of the most recent segment ofinterest and relevant features of a previous segment of interest aredisplayed using the one or more graphical elements, the displaying stepfurther comprising displaying: a line including one or more symbols thatindicate significant locations on the line, and a first symbol of theone or more symbols representing a value of a first relevant feature ofthe most recent segment of interest at a first point in time, whereinthe first symbol representing the relevant feature is displayed on theline in real time.
 18. The method as defined in claim 17, wherein thefirst symbol represents a trend of changes in the relevant features ofthe most recent segment of interest.
 19. The method as defined in claim17, wherein the mobile medical device includes a user interface on atouchscreen, the mobile medical device being configured to receive: (i)touch input to control the display of the relevant features includingdisplay scale and display speed, and (ii) touch input to control displaysettings and functions.
 20. The method as defined in claim 19, whereinthe user interface further comprises one or more icons representingtransmission and receipt of one or more ECG signals, the mobile medicaldevice configured for the transmission and receipt of one or more ECGsignals or of relevant features to and from a second network device. 21.The method as defined in claim 15, wherein the ECG waveform and therelevant features of the most recent segment of interest are displayedsimultaneously on a second network device.
 22. The method as defined inclaim 15, wherein each visual indicator is one of a dot or a dash. 23.The method as defined in claim 15, wherein each visual indicatorrepresents a singular point in time.
 24. The method as defined in claim10, wherein the display screen configured to emphasize the relevantfeatures of the most recent segment of interest corresponds todisplaying the relevant features of the most recent segment of interestusing one or more solid lines and displaying the relevant features of aprevious segment of interest using one or more dotted lines.
 25. Themethod as defined in claim 10, wherein each visual indicator is one of adot or a dash.
 26. The method as defined in claim 10, wherein eachvisual indicator represents a singular point in time.